1. Field of the Invention
The present invention relates to an apparatus for continuously heating an elongate textile article, such as yarn, tape or cloth, to thereby continuously dry or heat-treat the same.
2. Description of the Prior Art
Conventionally, in order for not impairing heating effect in such apparatus, attempts have been made to prevent cold outside air from entering into the heating chamber via its inlet or outlet for the elongate textile article to be heated. For example, Japanese Patent Post-Examination Publication (Tokkosho) No. 47-21276 discloses, as reillustrated in FIG. 3 of the accompanying drawings, a heating apparatus having a small-pressure box A which is mounted within the heating chamber at the inlet or outlet and into which a portion of superheated vapor for heat treatment is to be forced to equalize the air pressure of the small-pressure box to the pressure of air outside the heating chamber. However, a primary problem of such prior art is that a stream of heated air forced into the small-pressure box would flow out of the heating chamber via the inlet or outlet, thus causing a loss of heat energy. Another problem of the prior art apparatus is that, when an elongated textile article containing oil is heat-treated, smoke from the oil would develop and would be mixed in a circulating stream of heated air. The smoke from the oil together with the stream of heated air would then flow out of the heating chamber via the small-pressure box, thus contaminating the environment around the apparatus.